Yes, the CoolStream Duo does work with the Apple iPod HiFi speaker. Just plug the Duo into the 30 pin connector, and now your Apple HiFi is a Bluetooth speaker. You can stream music from an iPhone 6 or the latest Samsung using Bluetooth. Please note that a power adapter is not necessary.
For many iPod users the Apple HiFi dock has the best sound quality of the hundreds of iPod docking stations out there. But it was designed for the 12V Firewire iPod. So support for iPhones depended on power adapters that stepped down the voltage to today’s 5V standard. Then came the iPhone 5 with its lightning adapter, and some considered it time to mothball their Apple HiFi.
Thankfully the CoolStream Duo works with either a 12V or 5V docking station. The Duo goes on the iPod HiFi speaker, and it becomes a Bluetooth speaker.